Bar graphs showing effects of saline or cholinergic antagonists viz. mecamylamine (50 μg), atropine (30 μg), pirenzepine (10 μg), methoctramine (10 μg) or 4-DAMP (10 μg), on the antihyperalgesia produced by high frequency TENS. Atropine, pirenzepine and 4-DAMP significantly (*, p < 0.01, Tukey’s post hoc test) attenuated the antihyperalgesic effects of high frequency TENS, compared to saline group. Data are mean ± S.E.M. Contra = contralateral, Ipsi = Ipsilateral.